Apparatus for removing liquid from aqueous pulp

ABSTRACT

A stationary housing has an open lower end across which extends a perforate wall mounted for rotation about a central vertical first axis of the housing. The wall is driven in a predetermined direction and has at least two pressure rollers associated with it, being located in the housing above the upper surface of the wall and mounted for rotation about a second axis extending transversely of the first axis. The roller which is downstream as seen with respect to the direction of rotation of the wall has its circumference closer to the upper surface of the wall than the other roller. An admitting arrangement admits aqueous pulp into the housing so that the pulp is distributed in form of a layer on the upper surface of the wall and liquid is progressively expressed from the layer as the same is passed beneath the rollers. A receptacle beneath the wall collects the expressed liquid.

United States Patent 1191 Kloda et al.

1111 3,818,824 1 June 25, 1974 APPARATUS FOR REMOVING LIQUID FROM AQUEOUS PULP Inventors: Herbert Kloda; Rudolf Hies, both of Grevenbroich, Germany Maschinenfabrik Buckau R. Wolf Akttengesellschaft, Grevenbroich, Germany Filed: Sept. 20, 1972 Appl. No.: 290,524

Assignee:

References Cited UNITED STATES PATENTS l/1880 Ziegler 100/210 X 5/1907 Mills r r 100/158 R 11/1931 Leonard 100/173 X FOREIGN PATENTS OR APPLICATIONS Germany .i. 100/210 Primary Examiner-Lcon G. Muchlin Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A stationary housing has an open lower end across which extends a perforate wall mounted for rotation about a central vertical first axis of the housing. The wall is driven in a predetermined direction and has at least two pressure rollers associated with it, being located in the housing above the upper surface of the wall and mounted for rotation about a second axis extending transversely of the first axis. The roller which is downstream as seen with respect to the direction of rotation of the wall has its circumference closer to the upper surface of thewall than the other roller. An admitting arrangement admits aqueous pulp into the housing so that the pulp is distributed in form of a layer on the upper surface of the wall and liquid is progressively expressed from the layer as the same is passed beneath the rollers. A receptacle beneath the wall collects the expressed liquid.

25 Claims, 7 Drawing Figures PAIENTEBJUNZSIBM 2 SHEET war 4 APPARATUS FOR REMOVING LIQUID FROM AQUEOUS PULP sugar-cane bagasse.

The removal of liquid from aqueous pulp, for in stance from sugar-cane bagasse, is already known; the purpose of this is to make the bagasse as dry as possible so that it can be combusted. it is known from the art to remove liquid from the so-called diffusion bagasse by resorting to so-called three-roller mills of which that disclosed in U.S. Pat. No. 3,355,260 is representative, or to use worm presses or double-cone presses. None of these proposals have been found to be entirely satisfactory.

Thus, the amount of liquid contained in diffusion bagasse amounts to approximately 80 percent and this much expressed liquid is difficult to remove with threeroller mills, because it tends to swamp the mill. This has the disadvantage that it is not possible to make the bagasse as dry as possible in a single operation and in a single mill. As a result, if bagasse is to be de-watered by the use of three-roller mills, it is necessary to provide two or even three of these mills through which the bagasse must be passed sequentially before it has been dewatered to the desired extent. An attempt has been made to overcome this problem by dimensioning the known three-roller mills larger, with the resultthat the layer of bagasse which is subjected to expression of liq uid will be thinner. This, however, necessarily involves a more elaborate and expensive constructionof the mill, resulting in higher investment costs, as of course does the use of two or three mills together.

Worm presses, on the other hand, operate with a sliding friction under very high pressure. To attempt to express liquid from bagasse in this type of press means that high drive power is required, and this in turn requires high energy supplies. Also, the high pressure connected with the sliding friction which is inevitable in this type of press results in rather rapid and significant wear of the various components.

The third type of press which has been attempted to be used for this purpose, namely the doublecone press, permits the dewatering in a single operating step. This type of press has two conically configurated plates which rotate and define a certain angle withone another. To obtain the desired degree of de-watering in a single operating step necessitates high working pressures andthis in turn results in rapid wear of the components, in particular of the conical pressure plates. The latter, incidentally, are both vertically oriented which means that the expressed liquid must be evacuated under high pressure horizontally through the outlet openings, so that the liquid cannot run off freely, which in turn creates further problems.

In view of the disadvantages inherent in the prior art, it is a general object of the present invention to provide an improved apparatus which overcomes these disadvantages.

More particularly, the invention aims to provide an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, which is not possessedof these disadvantages.

Another object of the invention is to provide such an apparatus in which the expressing or removing of liquid 2 from the pulp can be effected in several adjustable operating steps.

Another object of the invention is to provide such an apparatus which avoids the high pressures required for removing the liquid from the pulp and yet obtains optimum de-watering.

In keeping with these objects,and with others which will become apparent hereafter, one feature of the invention resides, in an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, in a combination which briefly stated comprises support means and a stationary housing on the support means, such housing having an open lower end. A perforate wall extends across the open lower end and has a substantially horizontal upper surface. Mounting means mounts the wall on the support means for rotation about a central vertical first axis of the housing and drive means rotates the wall about this first axis and in a predetermined direction.

According to the invention at least two pressure rollers are located in the housing above the wall and are mounted for rotation about second axes extending transversely of the first axis. One of the rollers is spaced from the other roller circumferentially of the first axis and in the predetermined direction of rotation of the wall, the distance between the circumference of the one roller and the upper surface of the wall being smaller than the distance between the upper surface of the wall and the circumference of the other roller. Admitting means is provided for admitting aqueous pulp into the housing for distribution in form of a layer on the upper surface, so that liquid is progressively expressed from the layer as the same passes beneath the other and then beneath the one roller. Collecting means beneath the wall collects the expressed liquid. With the apparatus according to the present invention the incoming pulp is evenly distributed in form of a thin layer on the large upper surface or the rotating wall. Thereupon, the liquid is expressed from the pulp layer in several operating stages, namely in at least two stages, the one in which the first roller expresses liquid from it, and the second one in which the second roller downstream of the first roller expresses additional liquid. Because of the provision of these individual operating or pressing stages, taken in conjunction with the fact that the layer. of bagasse from which liquid to be expressed in the individual stages is rather thin, the pressures required for expressing the liquid can be maintained very low without, however, having to forego the desired degree of dryness for the end product, that is for the residue of bagasse from which th liquid has been expressed. i

It will be appreciated that the lower pressure required means a substantially lesser drive force and less energy for effecting the drive, and that this also results in a significant reduction in the wear of the various components. The large apertured or perforated surface of the wall assures a rapid and reliable removal of the expressed liquid so thata swamping or overflowing of the apparatus by the expressed liquid is avoided. in addition, the lesser pressures required assure that fewer non-sugar components of the bagasse are expressed, so that the expressed liquid or juice will have a greater purity than was heretofore the case.

The bagasse itself has very little inherent liquid, most of the liquid to be expressed being in form of water which was added to the pulp. Because of this the lesser pressure required according to the present invention is still sufficient to express any liquid which is accommodated in hollows of the pulp layer as well as liquid which adheres to the individual components of the pulp, for instance where fibers intersect. The compacting of the pulp components which is obtained in the operating stages of the apparatus according to the present invention assures that the hollows present originally in the pulp layer are eliminated, with their liquid content being expressed and removed.

To assure optimum efficiency of the liquid removal it is advantageous if the rollers (of which there can of course be more than two) are mounted so that they can be moved farther away from or closer toward the upper surface of the rotatable wall. This displacement can be effected hydraulically, mechanically, pneumatically or the like, and once a particular height of a given roller above the upper surface of the wall has been selected, the roller is pretensioned at the necessary pressure, so that it will resist yielding in direction away from the upper surface to such an extent that a desired pressing force between it and the bagasse layer is obtained.

The forces acting during operation on the perforate wall can be best withstood by the latter if the wall is annular in configuration and is provided in the region of its center opening with a journal, in addition to a journal in the region at its outer periphery. With this arrangement the further advantage is obtained that the pressure distribution on the wall is more equal.

The roller can be best journalled if the apparatus according to the present invention is provided with a central advantageously tubular tie element and/or with an additional annular housing or casing, with the inner ends of the shafts on which the rollers are journalled being themselves secured to the tie element or the casing. The tie element can extend through the central opening of .the annular wall and can be supported at its lower end, and because the center portion of the perforate wall cannot be used for expressing of liquid from the bagasse in any case, due to the fact that the rollers must be journalled at their inner ends adjacent the center portion of the annular perforate wall, the provision of such a center tie element and/or casing serves to utilize the center space effectively without detracting from the'efficiency of the apparatus.

The perforate wall may be planar, but according to the invention it may also be somewhat conical with an upwardly or downwardly directed opening angle which is large. If so constructed, the upper surface of the perforate wall would nevertheless still be at least substantially horizontal, because the cone angle will be large.

. The wall if given conical configuration has the advantage that it will have a greater surface area than if it were flat, but will have a smaller diameter. in terms of structural strength it is clear, of course, that the wall becomes stiffer and therefore most resistant to the stresses acting upon it. Particularly if the surface converges upwardly, the journalling of the rollers can be made particularly simple because the rollers can now extend almost completely horizontal and at right angles to the tie element or the inner casing surrounding the tie element.

The drive of the apparatus according to the present invention can be made particularly simple and advantageous if a separate hydrostatic drive is provided for the perforate wall as well as for each of the several pressure rollers. However, all of the drives can be supplied from a common hydraulic pump. The use of such drives has the advantage that the adjustments of the distance of the respective pressure rollers from the upper surface of the rotating wall can be carried out with very simple means.

The wet pulp or bagasse can be admitted into the housing from above, for which purpose the housing may be provided with a conical upper portion which carries an upwardly extending cylindrical casing accommodating a differential worm conveyor. The initial de-watering of the incoming wet pulp can be effected in this casing, in that the casing may be provided with a double-wall jacket the inner wall of which is perforated and the outer wall of which is provided with an outlet so that water can already run off the incoming pulp and be withdrawn through the outlet. The dry bagasse, that is the bagasse which remains after it has been subjected to the removal of liquid by cooperation of the perforate-wall and the pressure rollers, is removed, according to the present invention, above the rotary wall by means of a radially outwardly extending worm conveyor which is fixedly connected with the housing and which in the region of the perforate wall may be of conical configuration.

According to a further concept of the present invention the wet bagasse may also be supplied into the apparatus by providing the upper end of the housing with a planar closed cover having a laterally arranged admitting opening which is provided with a vertical chute the lower discharge end of which is located closely above the upper surface of the perforate wall. In the direction of rotation of the perforate wall the forward or upstream end may have an opening with an associated distributor roller. With such an arrangement, the wet bagasse can be evenly distributed over the surface of the perforate wall at the desired thickness.

Of course, when the liquid has been expressed from the bagasseit must be rapidly removed, by being allowed to pass through the perforations of the perforate wall. Advantageously, the upper surface of the perforate wall will be provided with radial grooves and a plurality of concentric channels, with the latter having a greater depth than the radial grooves. The grooves are advantageously of substantially triangular crosssection, a configuration which is especially advantageous if in direction of rotation of the perforate wall the cross-section of the grooves increases in depth. The lower edges of the groove cross-section are rounded to assure that the bagasse material cannot become pressed too tightly into the grooves and clog the perforations in the wall. It is further advantageous if the perforations,which communicate with the grooves at the lowest point thereof, are of conically downwardly diverging configuration, whereby a further assurance against clogging is obtained. The channels, on the other hand, are of trapezoidal crosssection and a wiper is associated with each of these channels which wipes in the channels and maintains the perforations clear.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments, when read in connection with the accompanying drawing.

FIG. I is a somewhat diagrammatic section taken on line I-I of FIG. 2;

FIG. 2 is a section taken on line lI-II of FIG. 1;

FIG. 2a is a diagram illustrating the arrangement of drive means for the apparatus in FIGS. 1 and 2;

FIG. 3 is a section taken on line III-III of FIG. 2;

FIG. 5 is a section taken on line V--V of FIG. 4; and

FIG. 6 is a view similar to FIG. 1 but illustrating a further embodiment of the invention.

Discussing now firstly the embodiment illustrated in FIGS. 1-5, it will be seen that the apparatus according to the present invention has one or more bases 12, for instance fundaments of concrete or the like. Mounted on these bases 12 is support means 11, here in form of a frame utilizing an upper support 12, a lower support 13 and several upright supports 15 connecting supports 13 and 14. A cylindrical housing 1 is mounted on the upper support 14 with its cover 46 which is provided with an inlet. opening 47 for the incoming aqueous FIG. 4 is a fragmentary enlarged detail. view of FIG.

pulp, the opening 47 being illustrated more clearly in FIGS. 3 and 6.

The housing I is stationary and has an open lower end beneath which there is mounted a rotating perforate wall 2 which in the illustrated embodiment is annular (see FIG. 1) and which is also of slightly conical configuration. The wall 2 is supported on an outer train of rollers arranged as a ring mount 3, and on an inner journal 16. Both the ring mount 3 and the journal 16 could be configurated differently, but'their construction as ring mounts utilizing a train of rollers permits them to absorb radial as well as axial forces. The journals 3 and 16 are supported on the support 13 via the components 61 and 62.

Extending through the center opening of theannular wall 2 is a tubular tie element 17 which is secured both to the carrier or support 14 and to the carrier or support 13, to the latter via the component 62. It thus provides for a center support for the entire arrangement. An inner casing l9 surrounds the tie element 17 with some clearance and is also connected to the upper support 14. In the region of its outer as well as of its inner periphery the wall 2 is provided with annular grooves 63 into which the lower edge of the housing 1 and of the casing 19 extends, respectively.

' Mounted in the housing 1 above the upper surface of the annular perforate wall 2 are pressure rollers 4, 5

and 6. These rollers are spaced circumferentially ofthe axis of rotation of the wall 2, and as FIG. 3 shows, the distance between the periphery of the respective roller and the upper surface of the wall 2 decreases in the direction of rotation of the wall 2. In other words, in FIG. 3 where the direction of rotation is indicated by the arrow A as it is in FIG. 2 also, the distance between the periphery of the roller 4 and the upper surface of the wall 2 is greatest, the distance between the roller 5 and the upper surface of wall 2 is smaller, and the same distance with reference to the roller 6 is still smaller. The rollers are each provided with an outer shaft 7, 8 or 9 and with an inner shaft 20, 21 or 22. The shafts may of course extend through the rollers or they may be shaft portions provided at the opposite ends of the rollers. In either case, the outer shaft ends are journalled in journals 31, 32 and 33, respectively, and the inner shaft ends are journalled in journals 34, 35 and 36. The

shafts 31, 32 and 33 are fixedly connected with the cylindrical housing 1, and similarly the journals 34, and 36 are fixedly connected with the casing 19. Each of the journals 3l-36 is connected with the respective housing l or casing 19 via a height-adjustable device 64 which permits the respective rollers 4, 5 and 6m be adjusted as to their distance from the upper surface of the wall 2 and to maintain them under hydraulic pretension, that is to subject them to such tension that they will not yield in direction away from the upper surface of the wall 2 except if a selected pressure is exceeded. The devices for adjusting and subjecting the rollers to pretension have not been illustrated because they are known in the art. I

The rollers 4, 5 and 6 as well as the wall 2 are provided with separate hydrostatic drives D (for the wall 2) and D D and D, for the rollers 4-6. These drives are all supplied by a common hydraulic pump. The drives and the pump as well as their relationships have been illustrated diagrammatically in FIG. 2a for orientation only, inasmuch as the detailsof such drives and their operation are well known per se. The connection of the drives has been diagrammatically illustrated in FIG. 2 with respect to the rollers 4-6, and of the couplings which effect such connection only the coupling portions 23, 24 and 25 have been shown in FIG. 2.

The bagasse which is admitted will be evenly distributed over the surface of the wall 2 in a thin layer, and this layer will then move first underneath the roller 4 where some of the liquid is expressed from it, and then underneath the roller 5 where more liquid is expressed because the roller 5 is closer to the upper surface of wall 2 than the roller 4, and finally under the surface of the roller 6 which is closest to the surface of the wall 2 and which expresses the residual liquid. The bagasse which has now reached the desired degree of dryness is then removed from the housing by means of a radially mounted screw or worm conveyor 26 which is journalled in a housing 27 which is fixedly connected with the housing 1 and has an appropriately located and configurated inlet. The shaft 28 of the conveyor 26 is mounted at one end in a journal 30 of the housing 27 and at the other end in a journal which is mounted on the inner casing 19, as shown in FIG. 2. The conveyor 26 also is driven by means of a coupling 29 via a nonillustrated drive. That portion of the screw 26 which is located in the region of the wall 2 is of conical configuration and thus the screw is accommodated both to the conical configuration of the wall 2 as well as to the different arriving quantity of the bagasse which is to be removed.

The supply of bagasse in wet state, that is as an aqueous pulp from which liquid is to be removed, can be ef-v fected in different ways according to the invention. Thus, FIG. 6 shows for instance that the housing 1 may be provided with a conical upper portion 37 which in turn may carry a cylindrical casing 38 accommodating a differential worm or screw 39. The casing 38 is provided with a double wall forming a. jacket or spacing between them, with the inner wall 40 being perforated so that water can run off the incoming pulp and can enter the space between the inner and outer walls of the easing 38. The outer wall of the latter is provided with an outlet 44 so that the water can be removed.

The screw 39 is provided witha shaft 41 which is journalled in journals 42 and 43, and at the lower end of the screw 39 there is provided at one lateral side an inlet chute 45 which extends through the inlet opening 47 of the housing cover 46. As seen in the direction of rotation of the wall 2, the chute is arranged upstream or ahead of the roller 4 and extends almost to the upper surface of the wall 2. The width of the chute corresponds to or is greater than the width of the rollers 4-6, so that the incoming bagasse will be evenly distributed over the entire radial width of the wall 2.

In FIG. 3 we have shown a supply arrangement for the incoming pulp, utilizing a vertical chute 48 and a separate distributor roller 50. The shaft 48 extends through the opening 47 of the cover 46 and the roller 50, which is located at that edge of the shaft 48 which is the downstream edge as seen with respect to the direction of rotation of the wall 2, assures an even distribution of the incoming pulp over the entire surface of the wall 2 in form of a thin layer. Furthermore, the roller 50 permits the thickness of the bagasse layer 59 (see FIG. 3) to be selected and adjusted at will.

The upper surface of the wall 2 is provided with evenly distributed radial grooves 54 having a triangular cross-sectional configuration which deepens in the direction of rotation of the wall 2, this direction being indicated by the arrow A. MG. 4, showing an enlarged detail, clearly illustrates the cross-sectional configuration of the grooves, and it will be seen that the lower comers of the grooves are identified with reference numeral 56 and strongly rounded to prevent the bagasse from becoming entrapped in these corners. In the region of the lower portion of each groove 54 the perforations 57 of the wall 2 communicate with the respective groove. These perforations are of conically downwardly diverging cross-section, as shown, and their upper open ends are covered upwardly by the projecting edge 65 which prevents clogging of the openings 56 because the vertical pressure exerted by the rollers 4-6 is intercepted by the edges 65 so that no bagasse can be pressed into the openings 57.

In addition, the wall 2 is provided in its upper surface with coaxial channels 55 which are concentric and of trapezoidal cross-sectional configuration. They have a greater depth than the grooves 54, inasmuch as they serve for cleaning of the grooves 54. The channels 55 are each provided with a wiper 58 which wipes them clean as the wall 2 rotates. v

In FIG. 4 the roller 6 has been illustrated in section, having the peripheral surface 6a which may be configurated as is known from the art, that is inaccordance with conventional practice in sugar-cane mills it may be fluted and provided with chevrons.

The direction of rotation of the wall 2 is indicated by the arrow A in FIG. 3, and the direction of rotation of the rollers 4, 5 and 6 as well as 50 is indicated by the arrow B in FIG. 4.

As has already been indicated earlier, the novel apparatus is particularly suitable for removing liquid from sugar-cane bagasse. It has also been indicated already, however, that it can quite generally serve for removing liquid from aqueous pulp, and it can also be used for the pressing of sugar cane. For instance, the apparatus according to the present invention may be used in conjunction with an already known sugar-cane milling installation from which it would receive the sugar cane to subject the same to an additional operation.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus for removing liquid from aqueous pulp, it is not intended to be limited to the details shown, since various modifications and structural changes can be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features essential to the invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended 1. In an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, a combination comprising support means; a stationary housingon said support means and having an open lower end; a disc-shaped perforate wall extending across said open lower end and having a substantially horizontal upper surface provided with a plurality of substantially radial grooves and with a plurality of concentric channels having a depth greater than the depth of said grooves; wiper elements extending into the respective channels; mounting means mounting said wall on said support means for rotation about a central vertical first axis of said housing; drive means for rotating said wall about said first axis and in a predetermined direction; at least two pressure rollers located in said housing above said wall and being mounted for rotation about second axes extending transversely of said first axis, one of said rollers being spaced from the other roller circumferentially of said first axis and in said predetermined direction, and the distance between the circumference of said one roller and said upper surface being smaller than the distance between the latter and the circumference of said other roller; admitting means for admitting aqueous pulp into said housing upstream of said other roller for distribution in form of a layer on said upper surface, so that liquid is progressively expressed from said layer as the same passes beneath said other and then beneath said one roller; and collecting means beneath said wall for collecting the expressed liquid.

2. A combination as defined in claim 1, wherein said support means comprises a supporting frame structure.

3. A combination as defined in claim 1; and further comprising roller mounting means mounting said rollers displaceable relative to said upper surface for varying the distance between the latter and the circumference of the respective roller.

4. A combination as defined in claim 3; and further comprising adjustable resisting means acting upon said rollers and adjustably resisting yielding of the same in direction upwardly away from said upper surface in response to pressures developing between said upper surface and the circumference of the respective roller.

5. A combination as defined in claim 1; and further comprising removing means for removing from said housing the pulp material from which liquid has been expressed.

6. A combination as defined in claim 5, said removing means comprising a screw conveyor fixed to said housing and extending above said wall substantially radially of the same and of said housing outwardly of the latter.

7. A combination as defined in claim 6, said screw conveyor comprising an elongated conveyor screw one portion of which extends over a portion of said upper surface; and wherein said one portion of said conveyor screw is conical in configuration.

8. A combination as defined in claim 1, said housing having an upper side provided with a planar cover; and wherein said admitting means comprises an admitting opening provided in said cover laterally offset from saidfirst axis.

9. A combination as defined in claim 8, said admitting means further comprising a chute extending from said cover downwardly towards said wall and having a discharge opening located closely adjacent said upper surface, said discharge opening being in part bounded by an edge portion located forwardly of said opening with respect to said predetermined direction; and further comprising a distributor roller mounted in the region of said edge portion for distributing the incoming pulp in form of a layer of said upper surface.

10. In an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, a combination comprising support means; a stationary housing on said support means and having an open lower end and an upper side; a hollow conical upper extension provided on and converging upwardly from saidupper side; a perforate wall extending across said open lower end and having a substantially horizontal upper surface; mounting means mounting said wall on said sup port means for rotation about a central vertical first axis of said housing; drive means for rotating said wall about said first axis and in a predetermined direction; at least two pressure rollers located in said housing above said wall and being mounted for rotation about second axes extending transversely of said first axis, one of said rollers being spaced from the other roller circumferentially of said first axis and in said predetermined direction, and the distance between the circumference of said one roller and said upper surface being smaller than the distance between the latter and the circumference of said other roller; admitting means for admitting aqueous pulp into said housing upstream of said other roller for distribution in form of a layer on said upper surface, so that liquid is progressively expressed from said layer as the same passes beneath said other and then beneath said one roller, said admitting means including a hollow cylindrical casing extending upwardly from said upper extension, and a differential feed screw accommodated in said casing; and collect ing means beneath said wall for collecting the expressed liquid.

ll. A combination as defined in claim 10, wherein said housing is cylindrical and its longitudinal axis is said vertical first axis, and wherein said wall is of circular outline. l

12. A combination as defined in claim 11, said mounting means comprising a roller-train ring mount engaging said wall from beneath in the region of its outer circumferential margin and operative for absorbing axial and radial forces transmitted to said ring mount by said wall.

13. A combination as defined in claim 12, said wall being annular and also having an inner circumferential margin; and wherein said mounting means comprises joumalling means engaging said wall at said inner circumferential margin thereof and also operative for absorbing axial and radial forces transmitted to it'by said wall.

14. A combination as defined in claim 13; and further comprising a tubular tie element extending through the central opening of said annular wall and beingconnected at its opposite ends with said support means.

15. A combination as defined in claim 14; and further comprising an inner tubular housing element surrounding said tubular tie rod with clearance.

16. A combination as defined in claim 15, said rollers comprising shafts mounting them for rotation about said second axes and having inner end portions and outer end portions which are respectively located closer to and farther from said first axis; and further comprising joumalling means joumalling said inner end portions on one of said elements.

17. A combination as defined in claim 13, wherein said wall is slightly conical and said upper surface diverges downwardlyand outwardly in direction-away from said first axis.

18. A combination as defined in claim 13, wherein said wall is slightly conical and said upper surface converges downwardly and in direction inwardly towards said first axis.

19. A combination as defined in claim 10, said casing having a perforate inner wall and an outer wall surrounding said inner wall and defining with the same a clearance into which liquid can enter from the incoming pulp; and furthercomprising an outlet provided in said outer wall and communicating with said clearance.

20. A combination as defined in claim 10, said wall being disc-shaped and said upper surface having a plurality of substantially radial grooves and a plurality of concentric channels, the latter having a depth which is greater than that of said grooves.

21. A combination as defined in claim 20, wherein the cross-sectional configuration of said grooves is sub stantially triangular, and wherein the depth of said grooves increases in said predetermined direction.

22. A combination as defined in claim 21, said grooves having rounded inner edges. I

23. A combination as defined in claim 21, said wall having a plurality of perforations communicating with said grooves at the lowest regions of the latter and having a cross-section which diverges in direction down wardly away from said upper surface.

24. A combination as defined in claim 20, wherein said channels are of trapezoidal cross-sectional config uration.

25. In an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, a combination comprising support means; a stationary housing on said support means and having an open lower end; a disc-shapedperforate wall extending across said open lower end and having a substantially horizontal upper surface provided with a plurality of substantially radial grooves and with a plurality of concentric channels,

said channels being of trapezoidal cross-sectional configuration and having a depth greater than the depth of said grooves; wiper elements extending into the respective channels; mounting means mounting said wall on said support means for rotation about a central vertical first axis of said housing; drive means for rotating said wall about said first axis and in a predetermined direction; at least two pressure rollers located in said hous' ing above said wall and being mounted for rotation about second axes extending transversely of said first axis, one of said rollers being spaced from the other roller circumferentially of said first axis and in said predetermined direction, and the distance between the circumference of said one roller and said upper surface being smaller than the distance between the latter and the circumference of said other roller; admitting means Llu 

1. In an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, a combination comprising support means; a stationary housing on said support means and having an open lower end; a disc-shaped perforate wall extending across said open lower end and having a substantially horizontal upper surface provided with a plurality of substantially radial grooves and with a plurality of concentric channels having a depth greater than the depth of said grooves; wiper elements extending into the respective channels; mounting means mounting said wall on said support means for rotation about a central vertical first axis of said housing; drive means for rotating said wall about said first axis and in a predetermined direction; at least two pressure rollers located in said housing above said wall and being mounted for rotation about second axes extending transversely of said first axis, one of said rollers being spaced from the other roller circumferentially of said first axis and in said predetermined direction, and the distance between the circumferEnce of said one roller and said upper surface being smaller than the distance between the latter and the circumference of said other roller; admitting means for admitting aqueous pulp into said housing upstream of said other roller for distribution in form of a layer on said upper surface, so that liquid is progressively expressed from said layer as the same passes beneath said other and then beneath said one roller; and collecting means beneath said wall for collecting the expressed liquid.
 2. A combination as defined in claim 1, wherein said support means comprises a supporting frame structure.
 3. A combination as defined in claim 1; and further comprising roller mounting means mounting said rollers displaceable relative to said upper surface for varying the distance between the latter and the circumference of the respective roller.
 4. A combination as defined in claim 3; and further comprising adjustable resisting means acting upon said rollers and adjustably resisting yielding of the same in direction upwardly away from said upper surface in response to pressures developing between said upper surface and the circumference of the respective roller.
 5. A combination as defined in claim 1; and further comprising removing means for removing from said housing the pulp material from which liquid has been expressed.
 6. A combination as defined in claim 5, said removing means comprising a screw conveyor fixed to said housing and extending above said wall substantially radially of the same and of said housing outwardly of the latter.
 7. A combination as defined in claim 6, said screw conveyor comprising an elongated conveyor screw one portion of which extends over a portion of said upper surface; and wherein said one portion of said conveyor screw is conical in configuration.
 8. A combination as defined in claim 1, said housing having an upper side provided with a planar cover; and wherein said admitting means comprises an admitting opening provided in said cover laterally offset from said first axis.
 9. A combination as defined in claim 8, said admitting means further comprising a chute extending from said cover downwardly towards said wall and having a discharge opening located closely adjacent said upper surface, said discharge opening being in part bounded by an edge portion located forwardly of said opening with respect to said predetermined direction; and further comprising a distributor roller mounted in the region of said edge portion for distributing the incoming pulp in form of a layer of said upper surface.
 10. In an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, a combination comprising support means; a stationary housing on said support means and having an open lower end and an upper side; a hollow conical upper extension provided on and converging upwardly from said upper side; a perforate wall extending across said open lower end and having a substantially horizontal upper surface; mounting means mounting said wall on said support means for rotation about a central vertical first axis of said housing; drive means for rotating said wall about said first axis and in a predetermined direction; at least two pressure rollers located in said housing above said wall and being mounted for rotation about second axes extending transversely of said first axis, one of said rollers being spaced from the other roller circumferentially of said first axis and in said predetermined direction, and the distance between the circumference of said one roller and said upper surface being smaller than the distance between the latter and the circumference of said other roller; admitting means for admitting aqueous pulp into said housing upstream of said other roller for distribution in form of a layer on said upper surface, so that liquid is progressively expressed from said layer as the same passes beneath said other and then beneath said one roller, said admitting means including a hollow cylindrical casing extendIng upwardly from said upper extension, and a differential feed screw accommodated in said casing; and collecting means beneath said wall for collecting the expressed liquid.
 11. A combination as defined in claim 10, wherein said housing is cylindrical and its longitudinal axis is said vertical first axis, and wherein said wall is of circular outline.
 12. A combination as defined in claim 11, said mounting means comprising a roller-train ring mount engaging said wall from beneath in the region of its outer circumferential margin and operative for absorbing axial and radial forces transmitted to said ring mount by said wall.
 13. A combination as defined in claim 12, said wall being annular and also having an inner circumferential margin; and wherein said mounting means comprises journalling means engaging said wall at said inner circumferential margin thereof and also operative for absorbing axial and radial forces transmitted to it by said wall.
 14. A combination as defined in claim 13; and further comprising a tubular tie element extending through the central opening of said annular wall and being connected at its opposite ends with said support means.
 15. A combination as defined in claim 14; and further comprising an inner tubular housing element surrounding said tubular tie rod with clearance.
 16. A combination as defined in claim 15, said rollers comprising shafts mounting them for rotation about said second axes and having inner end portions and outer end portions which are respectively located closer to and farther from said first axis; and further comprising journalling means journalling said inner end portions on one of said elements.
 17. A combination as defined in claim 13, wherein said wall is slightly conical and said upper surface diverges downwardly and outwardly in direction away from said first axis.
 18. A combination as defined in claim 13, wherein said wall is slightly conical and said upper surface converges downwardly and in direction inwardly towards said first axis.
 19. A combination as defined in claim 10, said casing having a perforate inner wall and an outer wall surrounding said inner wall and defining with the same a clearance into which liquid can enter from the incoming pulp; and further comprising an outlet provided in said outer wall and communicating with said clearance.
 20. A combination as defined in claim 10, said wall being disc-shaped and said upper surface having a plurality of substantially radial grooves and a plurality of concentric channels, the latter having a depth which is greater than that of said grooves.
 21. A combination as defined in claim 20, wherein the cross-sectional configuration of said grooves is substantially triangular, and wherein the depth of said grooves increases in said predetermined direction.
 22. A combination as defined in claim 21, said grooves having rounded inner edges.
 23. A combination as defined in claim 21, said wall having a plurality of perforations communicating with said grooves at the lowest regions of the latter and having a cross-section which diverges in direction downwardly away from said upper surface.
 24. A combination as defined in claim 20, wherein said channels are of trapezoidal cross-sectional configuration.
 25. In an apparatus for removing liquid from aqueous pulp, particularly from sugar-cane bagasse, a combination comprising support means; a stationary housing on said support means and having an open lower end; a disc-shaped perforate wall extending across said open lower end and having a substantially horizontal upper surface provided with a plurality of substantially radial grooves and with a plurality of concentric channels, said channels being of trapezoidal cross-sectional configuration and having a depth greater than the depth of said grooves; wiper elements extending into the respective channels; mounting means mounting said wall on said support means for rotation about a central vertical fIrst axis of said housing; drive means for rotating said wall about said first axis and in a predetermined direction; at least two pressure rollers located in said housing above said wall and being mounted for rotation about second axes extending transversely of said first axis, one of said rollers being spaced from the other roller circumferentially of said first axis and in said predetermined direction, and the distance between the circumference of said one roller and said upper surface being smaller than the distance between the latter and the circumference of said other roller; admitting means for admitting aqueous pulp into said housing upstream of said other roller for distribution in form of a layer on said upper surface, so that liquid is progressively expressed from said layer as the same passes beneath said other and then beneath said one roller; and collecting means beneath said wall for collecting the expressed liquid. 